Number of Good Ways to Split a String LeetCode solution in C++

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class Solution {
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 public:
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  int numSplits(string s) {
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    int n = s.size();
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    vector<int> left(26, 0);
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    vector<int> right(26, 0);
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    int left_count = 0, right_count = 0;
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    int splits = 0;
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    for (auto &it : s) {
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      right[it - 'a']++;
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      if (right[it - 'a'] == 1) right_count++;
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    }
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    for (auto &it : s) {
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      left[it - 'a']++;
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      right[it - 'a']--;
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      if (left[it - 'a'] == 1) left_count++;
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      if (right[it - 'a'] == 0) right_count--;
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      if (left_count == right_count) splits++;
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    }
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    return splits;
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  }
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};